As technology has developed, so have the ways in which viewers obtain video content. Not long ago, viewers could either watch video broadcast to their television sets or by traveling to the local cinema to watch a motion picture. VHS tapes and DVDs eventually emerged, both of which allowed viewers to watch the video content whenever they chose.
With the development of Internet protocol television (IPTV), communication companies are establishing networks for subscribers to watch video content. Generally, IPTV describes a system where a digital television service is delivered using Internet protocol (IP) over a network. The network used for IPTV may include the public Internet or a private IP network controlled by an IPTV service provider via a broadband connection known as digital subscriber lines (DSL), where the digital subscriber lines typically include conventional telephone lines with copper wire into households. Alternatively, the digital subscriber line may be fiber to the premises (FTTP). Telecommunication service provider companies that have begun offering DSL have limited bandwidth resources, particularly when delivering video over existing copper wire infrastructures.
In additional to television programming, many communications companies offer their subscribers video on demand (VOD) services. FIG. 1 is an illustration of a conventional system 100 that is configured to deliver VOD. As shown, a provider 102 is communicatively connected to a head-end server 106. Server 106 is used to store video content delivered to it from service provider 102. The server 106 is also capable of delivering video content 104 over a network 108, such as the internet or public/private packet switched network (PSN), for example. As shown, server 106 is configured to transmit video content in the form of data packets 104. The server 106 delivers the video content 104 via the network 108 to a DSL access multiplexer (DSLAM) 110. The DSLAM 110 operates to connect subscribers to the network 108, host video streams/Internet group management protocol (IGMP), and provide Ethernet transport of the video content. The DSLAM 110 further operates as a multiplexer to distribute the video content 104 through communication lines 112a-112n to set top boxes (STB) 114a-114n (collectively 114). Additionally, the DSLAM 110 may also communicate VOD requests from a particular STB 114 to the server 106 via network 108.
Today, VOD typically exists as a unicast video stream, as illustrated in FIG. 1. In a unicast stream set-up, there is one video stream for each subscriber requesting the video content. Therefore, if 100 subscribers request to receive a particular video file, 100 distinct copies of the video are delivered through the system. As shown in FIG. 1, STB A 114a initiated the request for video 104. After STB A 114a requested the video, server 106 initiated the delivery through network 108 and to STB A 114a. As shown, STBs B-N 114b-n did not receive the video. However, if STB B 114b requested the same video only moments after STB A 114a, duplicate copies of the video content 104 would simultaneously be streamed through the network 108. As can be appreciated, delivering video through a unicast video stream can bombard systems and dramatically reduce available system bandwidth when multiple subscribers request video content.
Therefore, service providers have begun to offer video content through a multicast video stream. A multicast video stream is illustrated in FIG. 2. Multicast stream network 200 is similar in most respects to unicast system 100. However, in contrast to the unicast video stream, multicast video streams are delivered to all subscribers connected to the network. As shown in FIG. 2, video 104 is delivered to all STBs 114a-n. In some versions of multicast VOD systems, multiple copies of the same video content are streamed through the network beginning at various intervals (e.g., every 15 minutes). This allows a video service provider to limit the number of video streams for particular video content, thereby limiting the amount of bandwidth dedicated to that video. However, multicast streaming requires the subscribers interested in the video content to begin watching the video content at a set time or at set intervals, which undermines the “on demand” aspect of VOD. Further, a substantial amount of bandwidth is still consumed by typical multicast VOD systems.
Additionally, electronic devices exist on the market that allow users to record video content based on the user's selection criteria. Digital video recorders (DVRs) allow consumers to record digital video content, such as video 104. Some service providers provide as an option to their subscribers the opportunity to lease a DVR from the provider, as opposed to the subscribers purchasing their own.
In light of the above, there exists a need for a system that provides true VOD while minimizing traffic on the network.